Hey guys,

I've got a 2004 Silverado, 4.8L with idle issues (sometimes - see below)
Mods are K&N FIPK 2, Flowmaster 40, Hypertech Tuning.

I'm trying to narrow it down, but I guess it could be any of the above, right?
Here's the scenario:

Start the truck, everything is fine.
Drive off, come to first stop sign. Engine idle speed lowers to 300 or 400 rpm, stumbles somewhat. Has stalled once or twice at this point.

It seems that this only happens when you have to come to a stop after the engine has just done some work.

I'm planning on checking/cleaning the TB tonight.
You can just clean it with some nice TB cleaner and some rags and a brush without taking it off, I hope!

Any input would be greatly appreciated!
Cheers!

p.s: I think it's been doing this to a lesser degree since I got it, and it's just got worse...

Hey guys,

I've got a 2004 Silverado, 4.8L with idle issues (sometimes - see below)
Mods are K&N FIPK 2, Flowmaster 40, Hypertech Tuning.

I'm trying to narrow it down, but I guess it could be any of the above, right?
Here's the scenario:

Start the truck, everything is fine.
Drive off, come to first stop sign. Engine idle speed lowers to 300 or 400 rpm, stumbles somewhat. Has stalled once or twice at this point.

It seems that this only happens when you have to come to a stop after the engine has just done some work.

I'm planning on checking/cleaning the TB tonight.
You can just clean it with some nice TB cleaner and some rags and a brush without taking it off, I hope!

Any input would be greatly appreciated!
Cheers!

p.s: I think it's been doing this to a lesser degree since I got it, and it's just got worse...

1. run can of seafoam through tankful. will clean everything in the fuel/injectors system
2. TPS would be my 1st culprit
3. ISCU will be my 2nd culprit. idle speed control unit, or whatever chevy calls their.
3. don't guess, check for codes at any major parts store. free. then here's a good link for you:
http://autorepair.about.com/cs/faqs/l/aa042603a_1.htm

also, if you have 2nd set of hands to hold idle steady, you can spray injector cleanr into the air intake hose.

good luck.

Ahh, yeah Idle Air Control ? (IAC)
Does the 2004 4.8L have one? I was told that it didn't... who knows.

Something I should have mentioned - checked for Diagnostic Trouble Codes - it's showing none.

Something I should have mentioned - checked for Diagnostic Trouble Codes - it's showing none.

every car has some sort of idle control system. turn it on cold, it'll maintaine higher rpms somehow, slowly lowered as it warms up. or offset idle for a/c. and it takes combination of fuel, ignition, and AIR to maintaine idle, so some sort of throttle pintle valve control should be employed. or air flow. btw - did you check your air filter?

if no codes, then i have posted the right link for you. time taking, but right. don't guss and guessplace the parts, it's mad circle.
all the best.

Clean the TB and make sure the MAF sensor is not covered with oil from the K&N filter.

//2000CAYukon

And with hypertech tunning.
Read and clear codes and.
Remove the hypertech tuning setup and set it back to factory for testing.
Has it also got the 160 thermostat?
Post back any codes in it now or what comes back after code clear.
You would be better off to run a stock AC air filter.
MT

Clean the TB and make sure the MAF sensor is not covered with oil from the K&N filter.

//2000CAYukon

i have just been through this week ago. dirty MAF throws SES light, "lean mixture bank one" code.

Cleaned the throttle body last night. That seems to have cured the problem!

Weird, that just a bit of gunk in the TB could cause that kind of issue!

Thanks to everyone for their hints and tips, you guys are invaluable!

Cheers!
Everyone have a great holiday weekend! :cheers:

Cleaned the throttle body last night. That seems to have cured the problem!

Weird, that just a bit of gunk in the TB could cause that kind of issue!

Thanks to everyone for their hints and tips, you guys are invaluable!

Cheers!
Everyone have a great holiday weekend! :cheers:


this is most always the solution with this low idle issue...simply clean the throttle body/IAC...and when this is done also clean the MAF since the air intake ducts will be removed...do this every 20,000mi. or more if you have dust/off road use.....

this is most always the solution with this low idle issue...simply clean the throttle body/IAC...and when this is done also clean the MAF since the air intake ducts will be removed...do this every 20,000mi. or more if you have dust/off road use.....

Whats the best way to clean the throttle body?

i have 93 5.7 &it has idled low since i bought it. put new idle control valve on it & it still idles so low about 300 rpm it almost goes dead. when its cold it cranks fine & idles about 800. when i turn the a/c on it idles up alittle but not quite enough, about 400